Candle filters generally employ a plurality of tubular filter elements which are closed at one end and are supported in a filter tank by a tube sheet from which they depend from into a filter chamber into which a fluid to be filtered is supplied under pressure. The filter candles are porous tubular members which are closed at the bottom and open at the top, and as the fluid flows from the filter chamber through the filter elements to a chamber above the tube sheet, solids which are entrained in the fluid are collected on the outside surfaces of the filter elements while the cleaned fluid flows out of the filter tank from the chamber in the upper part of the tank above the tube sheet. The filter elements extend through holes in the filter sheet and may be held in place in the filter sheet by many different devices including hold-down plates which are suitably mounted to the tops of the tube sheet over the tops of the filter elements.
One method of removing the solids which are deposited on the outer surfaces of the filter elements is to reverse the flow of fluid through the filter elements to dislodge the particles which had been deposited on the outside surfaces of the filter elements. This has been done without interrupting the operation of the filter by directing high pressure pulses of fluid into the interiors of the filter elements while the filter chamber remains pressurized. Various types of manifold designs have been used to the mount individual nozzles at the tops of the filter elements and to carry the high pressure fluid pulses to the nozzles. Where a large number of filter elements are used, the manifold designs become complex and are very expensive, particularly where the material from which the manifolds are made must withstand high temperatures of 1800 degrees Fahrenheit or more.